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Higher blood sugar in pregnancy tied to heart defects in baby, even if mom isn’t diabetic

five-heartsFor many years, doctors have known that women who had diabetes during pregnancy faced an increased risk of giving birth to a baby with a congenital heart defect. But now, for the first time, researchers have shown that the risk isn't limited to women with diabetes. A new Stanford study, publishing today in JAMA Pediatrics, found that women who were carrying a fetus with tetralogy of Fallot, the most common cause of blue baby syndrome, had higher blood sugar levels on average than women carrying healthy fetuses, even if the mothers were not diabetic.

From our press release about the research:

“Diabetes is the tail end of a spectrum of metabolic abnormalities,” said James Priest, MD, the study’s lead author and a postdoctoral scholar in pediatric cardiology. “We already knew that women with diabetes are at significantly increased risk for having children with congenital heart disease. What we now know, thanks to this new research, is that women who have elevated glucose values during pregnancy that don’t meet our diagnostic criteria for diabetes also face an increased risk.”

The Children's Heart Center at Lucile Packard Children's Hospital Stanford (where Priest, who is also a pediatric cardiology fellow, sees patients) is already a world leader in treating children born with tetralogy of Fallot. Pediatric cardiothoracic surgeon Frank Hanley, MD, has developed a surgical technique called unifocalization that allows him to repair the defect in a single, long operation - which is safer than the alternative of putting babies and children through several open-heart surgeries. Many families come long distances so their children can receive the lifesaving surgery.

Although the Heart Center team is glad to be able to offer state-of-the-art treatment for kids who already have heart defects, they would be even happier to know how to prevent such defects from happening in the first place. Genetics plays into some heart defects, but in most cases, the cause is a mystery.

So this new study, though relatively small with 277 subjects, gives a clue that the Stanford team is eager to follow with other investigations:

“I’m excited by this research because it opens up a lot of questions about how physiologic processes in the mother may be related to congenital heart disease,” Priest said. “Most of the time we don’t have any idea what causes a baby’s heart defect. I aim to change that.”

The study’s senior author, Gary Shaw, DrPH, professor of pediatrics in neonatal and developmental medicine, added, “There are several other kinds of structural birth defects, in addition to heart defects, that have been linked with overt diabetes. This new work will motivate us to ask if underlying associations with moderately increased glucose levels may be similarly implicated in risks of some of these other birth defects.”

I also chatted with pediatric cardiologist and Heart Center director Stephen Roth, MD, who pointed out a practical advantage of the new finding that hadn't occurred to me: We already know how to address elevated blood sugar with strategies such as dietary change, exercise and medications. If today's discovery is replicated in larger studies, it wouldn't be hard to translate it into action.

“It’s always wonderful to discover new information about the cause of a disease or class of diseases,” Roth told me. “And it’s particularly encouraging when we have the possibility of modifying the cause with existing therapies to reduce the likelihood that the disease occurs.”

Previously: Patient is "living to live instead of living to survive" thanks to heart repair surgery, Little hearts, big tools and When ten days = a lifetime: Rapid whole-genome sequencing helps critically ill newborn
Photo by emdot

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